Secondary battery, electronic device, and power tool

Abstract

Provided is a secondary battery including an electrode wound body having a structure in which a positive electrode having a belt shape and a negative electrode having a belt shape are stacked and wound with a separator interposed between the positive electrode having a belt shape and the negative electrode having a belt shape and an exterior can housing the electrode wound body, in which the positive electrode includes positive electrode active material layers on both surfaces of a positive electrode foil having a belt shape, the positive electrode has two edges being intersections of an end surface on a winding start side and surfaces of the positive electrode active material layers in sectional view of the positive electrode, and an insulating member having a length of 10 mm or more and 40 mm or less is disposed on a surface of the separator on the winding start side of the electrode wound body at a position facing at least one of the edges of a positive electrode.

1 . A secondary battery comprising:
 an electrode wound body having a structure in which a positive electrode having a belt shape and a negative electrode having a belt shape are stacked and wound with a separator interposed between the positive electrode having a belt shape and the negative electrode having a belt shape; and   an exterior can housing the electrode wound body,   wherein   the positive electrode includes positive electrode active material layers on both surfaces of a positive electrode foil having a belt shape,   the positive electrode has two edges being intersections of an end surface on a winding start side and surfaces of the positive electrode active material layers in sectional view of the positive electrode, and   an insulating member having a length of 10 mm or more and 40 mm or less is disposed on a surface of the separator on the winding start side of the electrode wound body at a position facing at least one of the edges of the positive electrode.   
     
     
         2 . The secondary battery according to  claim 1 , wherein
 the positive electrode includes a double-sided active material forming portion including the positive electrode active material layers on both surfaces of the positive electrode foil; and   a double-sided active material non-forming portion in which both surfaces of the positive electrode foil are exposed, and   the double-sided active material forming portion, the double-sided active material non-forming portion, and the double-sided active material forming portion are provided in order from one end on the winding start side to another end on a winding end side of the positive electrode.   
     
     
         3 . The secondary battery according to  claim 1 , wherein the insulating member includes a substrate layer containing a polymer material and an adhesive layer. 
     
     
         4 . The secondary battery according to  claim 3 , wherein the polymer material includes at least one of polyethylene, polypropylene, polyester, or polyimide. 
     
     
         5 . The secondary battery according to  claim 3 , wherein a thickness of the substrate layer of the insulating member is 10% or more and 60% or less of a thickness of the positive electrode. 
     
     
         6 . The secondary battery according to  claim 1 , wherein a width of the insulating member is greater than a width of the positive electrode by 1 mm or more. 
     
     
         7 . The secondary battery according to  claim 1 , wherein a protruding width of the insulating member from the separator is 1 mm or less. 
     
     
         8 . An electronic device comprising the secondary battery according to  claim 1 . 
     
     
         9 . A power tool comprising the secondary battery according to  claim 1 .